Radio apparatus



. June 25, 1929. G, w, plCKRD 1,718,431

RADIO APPARATUS Filed Oct, 14, 1921 3 Sheets-Sheet 2 'W' \\l\\ f vRADIO'APPARATUS. Application led October 14, 1921. Serial No. 507,663.v

This invention relates to radio apparatus bodiment of the invention mofor use in radio communication for recepadapted for direction finding;tion and transmission. *The invention in iig. 7 is a diagrammatic view.showing particular relates to Acombined open and the wiring of theconstruction of Fig. 6;`

closed aerials of the typedescribed in my Fig. 8 is a diagrammatic View.of another Patent 876,996, and in my pending appllcaembodiment of .theinvention more especire especially tions, 'Serial No. 368,903 filedMarch 26, ally adapted for elimination of static than 60 1920,and'Serial No. 379,405 iiled May 6, 4o'r direction nding. 1920, thepresent application constituting a In Fig. vl` is shown the now-familiarre- 10 continuation in part of application No. 368,- ception curve. of avertical loop lor closed 903. The apparatus disclosed in the patentaerial, in a. horizontal plane, consisting ofl aandapplicationsabove-mentioned relates to cosine curve drawn in polarco-ordmates. 65 aerials having different directional proper- This 1s anidealcurve; actuall ties in any given plane suchas a closed loop gives amore or less distorted ligure-of* aerial combined with an open verticalaerial eight, sometimes tending to an hour-glass in which the currentsset up-in the aerials 4shaptaand usually more or less iinsymmetriarecombined for unilateral reception, as in cal. n a vertical plane,including-the plane 70 direction finders and radio Compasses and of theloop itself, reception for a closed loo e for the elim nation of'staticas in transatis symmetrical, and the reception curve in Q)lantic'communication,'or both. this plane is a circle, as shown in Fig.2.' Heretofore, apparatus has been designed If t e loop is near theground, i't does not fory reception in a'horizontal plane, and thereceive from points below the horizon; and 75 reception characteristicsof aerials have been the reception curve for a loop in afvertcal studiedprincipally, if not exclusively, 1n plane including the loop is a.semicircle as that plane. illustrated infull lines. f' However, if theAn object of the present invention .1s to loop is elevated suflicientlyabove the surprovide .aerials having three-dunenslonal face of theground, such reception curve in, 80

characteristics designed to recei-ve useful siga vertical lane includingthe plane of the --nals directionally in all planes, i. e., a threeloopwill e a circle as shown 'in Fig. 2,

3o dimensional direction finder or radio compartly infull and partly inbroken lines. pass, and to eliminate static coming from This would betrue if the loop is placed aloft any point in altitude or azimuth, i.e., from as on an aircraft. Finally, the complete any direction inspace. f' three-dimensional reception surface of the lOn November 5,1919, I presented a 'paper loop is a torus, -not illustrated, but seearticle before the Institute of Radio Engineers on above referred to,Fig. 12; that is, a ldough- Static elimination by directionalrecepnut-'shaped figure with the contracted cen-` ti-on, in which paperI discussed the results tral portion tangent to a line drawn norof myinvestigations on static'and. the remally thru the center-of the loop.The sigeeption characteristics of aerials not only in .nificanceof thereception curves of Figs. l

40 the horizontal plane, but also inth'ree-diand 2 is obvious; that is,the closed loop can mensions. The paper with li ures Was pub- .receivemore or-less from all points in space lished in the Proceedings of theInstitute excepting only 'along a line passing no r- 95 ofRadio-Engineers,- for October, 1920, butl mally thru'its center. Thereception of a f I will briefly outline and discuss the receploop isalso dependent upon the plane of potional eharucteristics'of suchaerials in so l.larization'of thefwaves; that is, lthe orientafar asthey may serve to elucidate and eX- tion of the source or transmitter,and this plain' the present invention.

In the accompanying drawings, and the description thereof. The torus-Figures 1 to 5 inclusiveI are diagrams or shaped figure or surface ofrpception is, as

5e reception curves illustna, 'ngthe Vdirectional explained in thearticleftrue for sources of .properties of open angl/.closed aerials andIall possible orientation of the, source of their combinations; i waves.A further meaning of Figs.-1 and 2 10|- Fig. Gis an elevationillustrating one emis that maximum reception for a loop isg in is fullyset forth in Fig. 19 of the article,-100

loop; that is, for

- come solely from above,

all directions in the plane including -the a loop having its plane in aneast and west direction, the zone of maximum reception is a belt acrosst-hesky from east to west, reception decreasing to zero on the horizonat points north and south of the loop.

The so-called open antenna, which usually consists ot a vertical wire,short as compared with a wave-length, plane a simple circle recept-iondiagram, that is, it receives equally well from all points on thehorizon.l Such a diagram would be such as disclosed in Fig. 2, in whichthe antenna is arranged vertically ot' the point O, reception beingequally. in all directions in the horizontal pla-nc as indicatcd by thecircle. In any vertical plane passing thru the antenna, a quiteditl'crent reception curve results, as reception is a maximum on thehorizon, and decreases to zero at the zenith. The complete curve in anyvertical plane passing thru the antenna, therefore, would be atigure-of-eight such as disclosed in Fig. 1 and discussed in connectionwith the loop; that is, when the antenna is near the ground, itsreception figure would be so much of the tigure-of-'eight of Fig. 1 asis above the line A, B, Fig. 1. However, if thisantenna were spacedvertically from the earth a sufficient distance, the complete receptioncurve in a vertical plane would then be a figure-ot'- eight. In otherwords, the reception curve of an open antenna in a vertical planepassingthru it is the same as the reception curve ot a closed loop in ahorizontal plane.. Actually, as with the loopl or coil aerial, and forsimilar reasons, this ideal curve for the open ant-enna usually suffersconsiderable distortion, partly be anse actual vertical aerials have anappreciable horizontal length in most cases, and partly beca-usc ot'unsymn'ietrical or electrically-warpcd surroundings. The complete'direc-dimensional reception surface of the open antenna is thereforejust like the closed loop reception surface, being a torus, planesapart.

In this connection, there has been milch discussionas to the directionor directions from which static comes. However, if static the zenith, asymmetricalopen antenna would make a perfect static eliminator. Equally,if static came in on the receiving point with the same intensity fromall points in altitude and azimuth, it would be difficult to accountforthe wellf known freedom of the loop from static. But if we assume ingeneral that static is at its worst near the horizon rather than thezenith and comesfrom a point or a small arc instead of from'all around,the horizon, it will be obvious why the loop is a much bet-ter stat iceliminator than vthe open aerial.

It is now known, as a result of careful' has in the horizontal' butarranged 1n 'surface is difficult to measurements, that static wavescome in on the receiving station from the horizon, ife., with aiiractically vertical wave l'ront. See L. W. Austin, The lVavc-ItroutRadio-'llelegraphy \Vashington Acad. Sci. J. II, pp.101-106, March t,1921.

As disclosed in my patent above referred to and also in thc applicationsabove rcerred to, itis my practice to couple the open aerial and the'closed loop together with the open and closed acrials at approximatelythe same point in space 'relative to the transmitted wavelength,-(i. c.,the open and the loop acrialsarc either at thc same point in space, orare but a very small fraction ot a wave-length a.par t),-a1nl to add thecurrents received in the open and closed aerials in -phase in asecondary cir- ,cuit for affecting -a detector or indicator.

lIn such coupled or combined arrangements,

loop and open aerial ot it' (by vproviding a Angle in,

equivalent dimensions or by coupling ad` j'ustment, or by both), thecurrents open antenna are made `equal, in their effect upon thesecondary, to those 'from the loop, the result of this addition may beillustrated by a reception curve on the horizontal plane, as shownin'Fig. 3. As there illustrated, it will be seen that reception is at. a1na. \'imum from thel direction C A, is zero from the direction O-B, andhas intermediate values from other directions, the complete curve beinga cardioid, it heilig assumed that the distant transmitter is at a pointat the right of the figure and that the. coupling between the 4open andclosed aeria-ls and sccondary is so arranged as to add the currents inthe open and closed aerials. Such a circuit, employed as a directiontinder, givesthe. true bearing of the distant station, and does not, aswith the simple loop, lea-ve the direction indeterminate by 180. In avertical plane including the loop, the reception curve forfthe coupledloop and open/ aerial is also a cardioid, as shown in Fig. Lt. with amaximum on the horizon at Z, and zero on the horizon at B. Receptionfrom the zenith, that is, along the line OZ, being limited to the loop,has half the value of reception along the line O-L In a vertical planeat right angles with the loop and, passing thru the vert-icall antenna,the reception curve of the-combined system is a circle, `as indicated atY, Fie. 5.

The complete three-dimensional reception show in a two-dimensionaltigure or plan. In Fig. 5, however, I have illustrated the threeprincipal sections of thisreception surface. This rece )tion surfacesection, it willbe noted, is ma e up of a combination of the figures ofFigs. 3 and 4 arranged at right angles to each other, plus the surfaceY, arranged in a plane at right angles and passing thru line Z-N This-gure is a cardioid -of revolution,

from the apple.,

pending which may be. moresimply described as anwith the pit at theorigin O. From a conslderat-ion of the three-dimensional unilateralreception figure .of the combined open and loop aerials,

be seen that static originating at oints other than on thehorizon in thedirection of will either be Wealgthe distant transmitter ly received,or, if it ha pens to originate on the horizon at a point 180 fromthe-transmitter, it will not be received at all.

As fully discussed and disclosed in my coapplications above mentioned,the combined openaerial and loop such as shown in myPatent 87 6,996 isnot at present,

. however, the best arrangement for kreducing static. 'As the effect ofstatic on a receiving circuit is practically pure impact excitation,complex Waves will be s .et up in the two coupledcircuits-the loop andthe open antenna-With the result that. the ideal diagrams illustrated inFigs. 1 to 5 are but roughly approximated. Y These diagrams are,ofcourse, only true for steady state undamped wave reception, or forstatic reception on substantially aperiodie circuits.

The' types of combined closed loop andl open aerials as disclosed in myapplications above mentionedand in use at Otter' Cliffs near Bar Harbor,Maine, for transatlantic communication, are lconstructed .and designedprimarily with reference to the hori- 'zontal characteristics ofreception-andnot inregard to the three-dimenslonal receptlon.

Such apparatus, however, Was found to bel very satisfactory in.reception and inhthe` elimination of static, especially when used with avariable resistance inserted in 'either or both aerials such asdisclosed in Fig. 8, this resistance being for the purpose ofl damping,the oscillations caused' by static upon the coupled circuits of thereceiving apparatus as more fully described in said applications andhereinafter, such resistance being generally of the order of 'thousandsof ohms; for example, 1,000 to 10,000 ohms,

its exact .value depending upon the circuit ycharaeteristics,wave-length, etc.

. As a result 'of my investigations at Otter. Cliffs andstudy of aerialsin three dimensions, I have devised the arrangement of open and closedaerialsvdisclosed in@ Fig. 8

- as the most satisfactory, primarily for the elimination of static.Examination `of Fig. 5,wi1l show if this figure is turned thru 90`(lockwiseso that the vertical plane Y becomes the horizontalplane, averyfavorable reception surface results.' No energy such as static wouldbereeeived from the zenith and a very little' from the rest of thehemisphere until theyhorizon was reached On the horizon, from staticsources having all possible planes ofv polarization, there would bereception from' all directions, but

for signals from distant transmitters the.

as shown in Fig. 5, it Will y ltally relatively to the l'metrically withthe loo as to the reception surface.

the transmitter,`so that signal reception would be directional, and sothat the circle Y of Fig. 5 would be eight'such as derto turn throughface of al circuit, such as changed to a figure of the reception suracombined closed.

that shown in Fig. 1. In orloop and open vertical antenna adjacent theearth, and to obtain `the ladvantages of this invention, I found itnecessary t0 shift such vertical antenna thru 90 in the plane of theloop. This results in the construction illustrated ldiagnammatically inFig. l8- in which A' is a closed loop therewith a tuning justableresistance aerial 'having in, series condenser C and an ad- R. Arranged-horizonground and `sym- A v but -insulated therefrom is an open aerialB having inserted centrally thereof an adjustable con# denser C aroundthe terminals of which is a shunt having a coil L" coupled to a coilLs'in the closed' loop A forming an adjustable coupling M fortransferring in phase the energies received in the closed loop and 1nthe open aerial to one or the other, combimng them, and constitutingmeans for eliminating static. 'A secondary circuit S having a coil L2therein is adjustably coupled as indicated at N to coil L3, or, if sodesired,to coil L". The circ-uit S includes an suitable detecting meansand indicator (not illustrated) and may also include any amplifyingmeans. I have found it best to remove the cn'cnitllsclosed 1n Fig-8,somewhat from theearths'surface, and I have observed that 1n general, 1fthe lower part of the loop is'elevatcd some .five or slx meters from theground, the arrangement Will func'- tion sa.tisfa'ctorily.` In thisconnection, 1t must be remembered that, overland at least, Wave-frontsare not vertical, but are tilted forward somewhat `in i the direction ofpropagation. F or example, I- have found that at Otter Cliffs the wavesarriving fromfEur'opean stations were in'- elined approximately 15 fromthe vertical. Vhcn a tilted wave-front of Fig. 8, it is equivalent totilting the`horizon of this figure, with all that' that impliesReturning to the plane Y,

Fig. 5, Iit will be seen that if passes, the circuit.-

assuming that 'it is. now in a horizontalI plane, be rotated slightlAcounter clockwise around- C-z-'D as an axis, one-half of the receptionsurface will bemore or less subm'erged (below ground), so that receptionwill be unilateral. This change of position of the reception surface' issecured in the" physical" embodiment of the invention by angle, therebysuppressing practically encircuit free from disturbance.

.swlnglngthe c ircuitI of Fig. Sthru a slight all by the combination,

Cil

source of static tending vzontal antenna B is either condenser Cinserted at its center. coils L In the construction of Fig. 8, thehorifeebly receptive or non-receptive as to the transmitted signal, theloop B being so positioned, with its plane in line with the distanttransmitter, Aas to receive the signal with maximum intensity. Staticwavesl coming from overhead are received by both collectors A and B andare equalized and opposed by couplings L L3 L2 which are adjustablel andreversible. Static impulses originating near the horizon at lpoints atright angles to theantenna B will be received by the open antenna onlywhen their plane of polarization is other than vertical, and I havefound that in general all waves arriving from the horizon are verticallypolarized, perhaps due to-attachment to the earth, and hence are eithernot received at or at most but eebly. On the lother hand, staticimpulses arising at points near the horizon in the plane of the loopwill not affect aerial B, and hence cannot be eliminated without sotilting the apparatus that the horizontal aerial B' is affected and thestatic energizes in the two aerials then equalized and opposed by thecouplings. In the latter case, inasmuch as the horizontal aerial B istilted relative to the ground to cause it to be normal to the tiltedtransmitted waves, Vstatic waves coining from these directions will alsostrike the open aerial B at an angle and set up 'oscillations which canbe made equal to and opposed with the static oscillations in the loop.

In an embodiment of the invention of Fig. 8 as actually constructed andused, the loop `Alconsisted of seventurns of number 16 Brown & Sharpgauge ,copper wire (1.3 mm. diameter) spaced 10 cm. (4; inches) apart ina solenoidal coil, 30 meters (91.5 feet) long, 7 meters (21.4 feet)Ihigh and i with the lower conductors of the loop about 4 meters (12.2feet) above the ground. The open horizontal antenna single wire meterslong, with a Variable The were 2O millihenrys each,

Pre-

and L and the resistance R was 1000 ohms.

liminary tests having indicated that the open antenna. B receivedmaterially less energy `than the loop A, the resistance R was thereforeplaced in the loop in order to render thecurrents in the loop and openaerial more nearly equal, thereby requiring and adjustment of thecouplings.

The apparatus of Fig.' 8 may be mounted,

if so desired or convenient, on suitable universal mountings such asdisclosed in Fig. 6, which 4will be more fully described `hereinafter,inorder that the combined closed loop and `open antenna may be locatedin the most advantageous to*the-transmitteror with reference to the topreventthe clear reception of the'signal, and if so'desired the able' orrequired it. Conductors 16 B consisted ot a. j

tuning condenser C less variation equal, and added together any relationwith reference and reversible for the purpose of equalizing andconcelling the static energies, and for this purpose it is'advisablethat reversing switches such as disclosed in my above-mentionedco-pending applications be employed.

Referring to Figs. 6 and 7, I have illustrated a form of the inventionwhich is primarily adapted for use as a radio compass or directionfinder on airplanes or balloons or for the purpose of determining fromany station the location of distant- 'airplanes or other airships whentransmitting.

Fig. 7 is a diagram of the circuits involved in the mechanicalarrangement of Fig. 6. In Fig. 6 I have illustrated a frame 11 ofinsulating material, having crossp-ieces 12 of similar insulatingmaterial. On cross-pieces 12 is secured a loop vA of wire forming amultiturn loop of any suitdimension. As here illustrated, this loop A isso wound lthat the several turns thereof same plane and spaced from.each other, altho they. may be wound in any suitable manner asconditions may require. The ends of the loop A extend atv points 13 and14 into shieldingl box 15 secured to frame 11 and containing theadjustable. elements of the apparatus as disclosed diagrammatically inFig. 7. Mounted at diametrically opposite lpoints on the n alined twometal rodsi B constituting an open' aerial structurally distinct fromclosed. loop A in the sense of being insulated from and 17 electricallyconnected to the rods B extend into the box 15 points 18 and 19 withinwhich they are associated with the adjustable devices more fullyillustrated in Fig. 7. 'The loop A has in series with it an adjust: bletuning-condenser G (Fig. -7) and an inductance L .(Fig. 7) within box15, (Fig. (3), while the open aerial B has a similar inductan'ce L (Fig.7) shunted around which is a variable all /within box 15 (Fig. 6). Theinductances L and L (Fig. 7 constitute an adjustable and reversiblecoupling M, whereby the signal currents set up in the open and closedaerials are made and the static currents are made equal and opposed iffor reason this is advisahle. I have not illustrated the specific meansthe condensers C and C' and couplings L and L3, as any well-known meansmay be .'utilized, such as knobs` or handles projecting open aerial vadded together thru couplings. L and L*l lie substantially in the 10oframe 11 (Fig. 6) are t or adjusting.

and are then transfer-red to a secondary circuit S thru an inductance L2pled at N to inductance L3. The secondary circuit S has associatedtherewith any suitable detector and usual condenser 21, which parts arelocated within casing 15, (Fig. 6) and leads 22 therefrom extend outsideof the casing and are provided with a filter, diagrammaticallyillustrated as choke- 'coils23, these being connected by leads 22 to atelephone receiver 24, Fig. 6.- This filter, which for some purposes mayconsist simply of a pair of choke coils, acts toprevent any disturbingaction either from the capacity-of the telephone receiver 24 to theoperators body, or from any energy which might be picked up by these`leads or by means of any high frequency energy drainage from the systemcontained'in the box 15. The fral'ne 11-12 supporting the erials A and Bis mounted on an axis journaled in a yoke 25, the frame being rotatedabout its horizontal axis by turning knob 26 which is attached to frame1112 and rotatable therewith. A suitable dial 27 attached to frame.l1-12 and rotating therewith co-operates with an indicator 28 fixed. toyoke 25 for indicating the angular positionin degrees of the loopand'aerial assembly carried by the frame. The yoke'25 is rotatable abouta vertical axis 29, which in turn is rotatably mounted on a base 30. Theposition of the rotatable yoke 25.

served by frame 11 and its aerials in azimuth is obmeans of a dial orgraduated circle 31 fixed to the axis 29 and therefore fixed withrespect to the base 30. The dial 3l co-operates with an index 32 fixedto the It will be s'een that the aerials are mounted rotatably'on both ahorizontal and a vertical axis. Both rotations can be imparted to thesystem by suit-1 ably manipulating knob 2G.

In the practice of my invention, unless the loop A is. of unusuallylarge enclosed area or the sending station is nearby, the secondarycircuit S preferably is supplemented by a suitable number of steps ofamplification in the manner now well-known in the art. 4After both theopen and closed circuits are tuned together and to the distanttransmitter, the couplings M and N are adjusted by successive trial sothat when the I loop and open aerials are in their position of maximumreception, the energy delivered to the secondary circuit is the samefrom each. the apparatus into the null reception position Where thecurrents are equal and opposite in phase and should then have no leffectupon the secondary circuit.

Inasmuch as the open circuit collector B leads the loop 'A in phase by90, these two circuits are coupled together as Well as to the`secondarycircuit-AS to preserve this phase relation; The currents are first addedvariably cou-- bearing of the sired.

This is best determined by swingingtogetherin'phasein the closedcircuit'A, and then the combined energy is transferred to the secondaryS, where it actuates any suitable indicator 24 (Fig. 6). For maxi-A mumreception, with Vadditive coupling the apparatus when-mounted as in Fig.6 is so swung that'the plane of the loop'includes the distanttransmitter (except under such circumstances as obtain when thetransmitter is in the same vertical plane as both the loop and the openaerials and is horizontally displaced With respectto the axis of knob26) and at the same time the open antenna B is normal to a line joiningthe receiving apparatus and transmitter. Similarly, the position ofnoreception is 180 from that,

such position being secured 'by swinging the loop thru 180 on the openantenna as an axis without changing the position of the open antenna. Asis common practice with two-dimensional direction finders employing myloop, the null point preferably is. used for determining the bearing ofthe distant station. The apparatus is swung in altitude and azimuthuntil a point of zero signal is reached, and this determines the distanttransmitter in three dimensions, i. e., its 'altitude rand azimuth.

The tuning of the several aerials to the desired wave length may be donesubstantially as follows. lFirst, cut, out the closed loop circuit as bylooseningthe coupling between it and the open circuit or by di.- rectlyopening the loop circuit at some point (not illustrated). Then vary thecondenser C (or its equivalent inductance) until the maximum signal isobtained in the open aerial. Then lopen or otherwise remove from thecircuit the open aerial vvandtune the lclosed circuit by means of theconenser 'C until maximum response is obtained. Then restore the opencircuit, and the combined system is ready for use. The tuning can bedone in the reverse order if so de- In each case the a'erials should bereceptively positioned relative to the distant transmitter. Altho I haveillustrated inductances L', L2 andL3 as being more sat-isfactory andeasier to manipulate, yet it is to be understood that any.. suitablemeans of coupling the open and closed circuits may be employed. TheAopen aerial may be tuned by an inductance if so desired such astheinductance L.

It is necessary that the currents in the two circuits A and B when attheir maximum Y,be equal in their effect upon the secondary S in orderto secure a null point on opposition orthe maximum signal upon additionof the equal currents. Otherwise, the reception characteristic curvesdisclosed in Figs. 1 to 5 will not apply. A change in degree lofcoupling, of course, changes the amount of energy transferred from onecircuit to theother (Figs. 6, 7, and 8), and' sistanee R therefore perwhereby the altlio it would be possible to' so proportion the dimensionsof the open and closed circuits that their reception wouldbe equal, itis much easier to make the adjustment by simple change in coupling.Furthermore,- inasmuch as the received current in a loop follows adifferent law of variation upon change of wavelength from that of anautenna, a given loop and open aerial would he in adjustment only at onewave-length, however carefully they were constructionally proportioned.lVhen the combinedj open and closed'aerials of the present invention areso located as to give a null point or. no response with reference to adistant transmitter( this means that the current in the loop and openaerial are equal and opposite and they cancel out in respect to thesecondary and no signal results. single simple loop has two null pointsin a horizontal plane, Fig. 1, which are', of course, the two lilies'normal to the loop; but when the single loop-is combined with an openantenna, there results but one null point, and this is 90 from the nullpoints of the loop alone, Fig. 3.

The function of the resistance R in series with the loop, Fig. 8, ifused, is to prevent the impact excitation of static or otherdisturbances from setting up complex or coupling waves inthe system as awhole. Such complex'oscillations result from the successive transfer andretransfer of energy between coupled circuits` of feeble damping and:gre objectionable in my invention because they tend to destroy orimpair the directional reception of the system on which the eliminationof disturbances depends. By increasing the damping of the loop aerial,which is most readily done by the insertion'of the resistance R as.shown in Fig. 8, such transfer and retransfer of energy is prevented andno coupling waves are formed. The preferred place for the insertion ofthe res'. tance R is in the aerial insertion of the resistance thecurrents in the two aerials When the open antenna it is preferable tothe loop. 'Phe reforms two functions: first, the damping of the systemto' prevent complex wave formation, and second, the reduction of thecurrent. in the closed circuit to approximate equality with that .intheo en circuit.

In using t e circuits disclosed Vi'n Fig. 8, -the operator lfirst opensthe antenna circuit, then tunes the closed circuit.' to the desireddistant station by first coupling the .loop with the secondary S andnoting the signal strength as the capacity C is varled. During thistuning, it is advantageous to reduce the resistance R to zero in orderto note the effect of the tuning more readily. When the maxitends tomake more nearly equal. is horizontal, Fig. 8, insert the resistance inA wavelength and constants -and finally slightly retunes as that ofFigs. 6 and 7 telephone, the magnetic loop of circuit A is opened andithe open lantenna closed.v The open antenna circuit is then timed to thesame distant station by varying inductances L or L'-l until maximum'response is obtained in the secondary circuit S. After both open antennaand magnetic loop circuits are tuned, the resistance R is increased fromzero until the maximum static elimination is obtained, this resistance Rbeingl a non-inductive variable resistance having a range say from zeroto some thousands or tens of thousands of ohms. In aerials of the sizeand dimensions herein specified, this resistance will be, when in use,of the order of some 'hundreds or thousands of ohms, depending upon theof the circuits. Then the operator varies the coupling between theinductances L and L until au is reached, the loop and open antennacircuit.. These steps may be performed in any desired order and may berepeated until the best reduction of disturbance is noted. r[he effectof these various adjustments seems to be to produce in the two aerialscurrents due tostatic which are opposite `in effect upon the secondary,so that when they are For this purpose, where the aerials are notfurther reduction in disturbance added, their effect is nil. 1

rotatable, it is preferable that the coupling coils be reversible, sothatthe static energies can be opposed, reversing switches for thispurpose being shown in my co-pending application, `Serial No. 379,405,above-mentioned. to the directional properties vof the system, are notin' general equal and opposite in their effects upon the secondary butadd to produce a useful signalthe currents due to staticdisturbances inthe two aerials be opposed in their effect upon the secondary, orotherwise they would add to produce a strong disturbance. To en surethis, the operator may reverse one aerial with respect to the other byreversing the coupling coils as by switches illustrated in saidapplication. y

The circuit arrangement of Fig. '8 as well sirable effects ofout-of-phase current in the system present 'when the open aerial is directly connected, to and forms a part of the loop, as disclosed in Fig.3 of my Patent 876,996 above-mentioned. In thepresent invention,out-of-phase currents are prevented by noty connecting the magnetic loopto' earth at all, but employing an open antenna which forms no part ofthe loop, altho it is within the scope ofthe invention to use anycombination of closed aerialy securing unilateral reception and a nullpoint from overhead.

It is important that avoids the undeloop and open horizontal' The signalwaves, however, owing in the loop circuit 15 In the systems illustratedin the accompanying figures, means for bringing into phase' both sets ofcurrents in their action on the receiving apparatus consists inemploying the coupling between coils L and L3 and L2, the two tunedcircuits being coupled together, energy in the form of oscillating oralternating current ofcone circuit being transferred to the other bymeans of such coupling. In the transfer, the phase is changed by 90, sothat in this system the currents flowino` in the open circuit normally90 out ofgphasewith currents flowing transferred by Way of the couplingsbetween coils L and L3 to the loop `circuit are changed in the phaseby90. and are-so made equal in phase with the currents already existingin the loop circuit.

In theuse of combined openfian'dfclosed aerials, primarily for thereception of signals and the elimination of static (Fig. 8) as or radiocoinpasses.

in Fig. 6 will serve as a distinguished from purely'direction finding(Figs. 6-7), the dimensions arc the closed coil distant transmitter Vortransmitters; the static being preferably eliminated by an uadjustmentor manipulation of'the coupling coils as described in m copendingapplication, Serial` No. 379,405. The same and possibly moresatisfactory results as to the elimination of static may be obtained .bymounting the' combined open and closed "aerials in the manner disclosedin Fig. 6, but this method is adapted for the smaller-sized aerials suchas direction finders preferably so located that. isl in line with theciples involved, however, are the same, and bythe addition of theresistance R disclosed in Fig. 8 to the circuitsof Fig. 7, the devicevery useful eliminator of static whenever necessary. When theconstruction of Fig. 6 is rotated to bring the open aerial into thehorizontal and clirected toward the distant transmitter, we havethepositions of' aerials as shown in F1g.'8. VThe construction shown inFig. 8 is .therefore preferably fixed on account of the over-all size ofthe aerials, altho even in the lack of a universal mounting as in Fig. 6

the openaerial Bof Fig. 8 may be and preferabl istiltable about ahorizontal axis in order to submerge its characteristic curve, Fig. 5,as described above so as to further decrease the effects of static. I

The aerials above-described are .adapted for use not' only in4 receivingbut also in transmitting. In receiving, any welleknown receivingapparatus or detector, such Vas crystal detector or audion, may be used,either with or without association therewith of steps of amplificationas is well known in the art, the detector and amplifier equipment useddepending upon the dimensions of the receiving aerials and the^power and.dis-

The action and prin-y tance of the transmitting station. vWhen used fortransmitting, afsuitable source of high frequency current replaces thedetector circuit.

' It is believedthat while static disturbances may arrive at a receivingstation from .various directions in altitude'and aximuth, the greaterpart of the disturbance coincs in on the receiving station fromthehorizon. According to my observation on y the North Atlantic coast,the lessl bothersome form of static appears to come indeterminately frommany points in the hemisphere, altlio with a preponderance toward thehorizon. more bothersome forms of static, however, are localized and onthe North Atlantic coast come mainly` from the southwest, so that byadjustment of the apparatus as described, their effects are greatlydiminished. 4

In the use of a universally-mounted aerial The as shown in Fig. '6 asastatic eliininator ,'.it

may be preferable under some circumstances to so locate the loop andopen antenna with reference to the-source of static that it is in largemeasure eliminated. This can be determined by so positioningthe loop andopen aerial,'by moving them on It-he'iraxes, that the static effectsare-the least noticeable. 'Thereafter the static-can'be totallyeliminated by equalizing and opposing the static currents in the twoaerials by manipulation and adjustnient of coupling coils, leaving asuiiicient amount of useful the loop' and open used as a directionfinder,

their vertical axis,

aerial are/ rotated around orv horizontal axis, heard, that is, when(Fig. 5) the pit or null point of the cardioid reception surface is.

signal energyto bei audible.- Where the, apparatus of Fig. 6 is or both,untitno signal is f In lorder Ito obtain neutralization and oppositionof static, it is necessary that the static currents received by thecollectors A and B when. combined musthave substantially the sameamplitude, frequency and decrement -or'l damping. `In other words,neutralization only takes .place when the energies are at every instantduring the wave train produced by static equal and opposite. This resultis secured byl the present invention.

It is to be understood that the invention is not limitedto theembodiments and fea-- tures specifically shown and described herein, butthat such embodiments and features are. subject to Ichanges andmodifications without invention.

any departure from the spirit of the and an open antenna ing disposed insubstantially the same plane I claim 1. Three-dimensional directiveradio apparatus comprising aerials having different directionalproperties but arranged in the same plane; means'for pivoting saidaerials permitting their simultaneous movement to any angular positionin space. \\'liile. 1m\in Vtaining them in their said common plane; anda local circuit coupled to said aerial system.

2. Three-ilimensional directive radio re.- ceiving apparatus comprisingopen and closed aerials, means for adding and detect` ing currents`therein; and a universal mounting for both said aerials whereby they maybe simultaneously shifted into' any desired angular' position in space.while, maintaining their relation to one. another.

3. 'llmee-dimensional directive radio apparatus which comprises anaerial system including two aerials of ditlerent directionalcharacteristics, namely a closed loop aerial aerial, said aerials beandsyn'nnetrically with respectl to onel another and inductively coupledtogether, the coupling being adjustable and reversible to permitequalization and cancellation of static energies, the open aerialforming no par-t'of the closed aerial, the closed aerial being in-Asulated from earth, and the open aerial being arranged generallyparallel to the earth; and meansfor tilting the opemaerial about ahorizontal axis to submerge its charactei-istie curve and decrease theetlects ot static` 4. Directional radio/apparatus comprising a base, ayoke pivoted toV said base on a vertical axis, a fram-e pivoted to saidyoke on an axis at right angles to the first-mentioned axis, open andclosed acrials having variable coiuilings and tuning devices supportedby said trame, and a bof; mounted 'on said frame and containing said-\-'a.riable couplings and tuning devices. V

5. 'lhree-dimensional directive. radio apparatus'which comprises anaerial system including two aerials ot different. directionalcharacteristics, namely a. closed loop aerial and an open antennaaerial, said aerials being disposed in substantially and symmetricallywith respect to one another, and being indue-tively coupled toeether buteach insulated from earth and from one another, the-open'aerial formingno part of the -closed aerial and being erally parallel to the earth;and means moving the open aerial. Y

l6. .Tlnee-dimensional directive radio receiving apparatus comprisingaloop aerial, an open aerial, a secondary circuit` coupling means torsaid aerials and circuit, and a universally movableiramc on which saidaerials, circuit and coupling means are mo'unted.

'i'. Three-dimensional directive radio apfor ft'rame, couplings betweensaid and means the same plane 'system comprising paratus comprising aframe, a loop aerial and open aerial mounted on said frame, tuningdevices :tor said aerials mounted onthe frame, a secondary circuitmounted on the aerials and circuit and mounted on the frame, and meansfor supporting said frame for substantially universal movement. r 8.'lhree-dimensional directive radioapparatus comprising a frameloopaerial mounted thereon, an open aerial also mounted on said trame andinsulated from said loop, means for combining the currents set up insaid aerials and detecting .the same, and a substantially universallymovable mounting for said aerials.

9. Three-dimensional directive radio apparatus comprising open andclosed aerials mounted tor movement substantially uniersally, means forcombiningthe curr-,ents set up in said aerials and detecting the saine,

for inox-'ing said aerials simultaneously and substantiallyuniversally..

` l0. Three-dimensional directive radio apparatus comprising a. framehaving a closed loop aerial mounted thereon, an open aerial comprising apair of rods mounted in alinementon said frame, means forcoupling saidserials together and tuning the same and mounted -centrally on saidframe, a secondary circuit coupled to said aerials and mounted ontheframe, and a mounting for substantially universally pivot-ing said`frame and aerials.

ll. A three-dimensional directive radio system comprising a closed loopaerial, two metal rods mounted substantially diametrically ofthe loopaerial and arranged symmetrically therewith about a common point andconstituting parts of an open aerial; means for coupling such closed andopen 'aerials with one another; means sired angular' position circuitcoupled tosaid system and .containing a telephone receiver; and means inthe telephone circuit'for preventing disturbing action on said aerialsystem bythe ytelephone leads.

12. A three-dimensional directive radio a closedloop aerial, an openaerial arranged substantially horizontally relative to ground and vsymmetrical with the loop aerial about a common point, the. two aerialsbeinglocated at aproximately the same point in space relative to thelength ot the transmitted Waves; means ,for

" coupling said loop and open aerials; means permitting thelsimultaneous tilting of said aerials to cause the open aerial tobenormal to tilted transmitted waves; said open aerial being insulatedfromthe loop aerial; and an operating circuit coupled to saidcombination ot loop and open aerialsl- 13. Three-dimensional directiveradio aphaving a closed for sWing- `ing said aerlals simultaneously toany de- 1n space; a secondary paratusjcomlprising open and closedaerials symmetrical y disposed with respect to one another about acommon aerial being arranged in a substantially hor- -izontal plane andnormal to the transmitted wave-front, a coupling between said aerials,and a secondary coupling. i

14. A three-dimensional directive radio directive system comprising aclosed loop aerial; an open aerial normally arranged substantiallyhorizontally relative to the ground and symmetrically with said loopaerial about a common point, said open aerial beingcoupled to but`otherwise insulated from the loop aerial; means for moving said aerialssimultaneously to any desired angular position in space; means forequalizing the currents in t e loop and open aerials, comprising aresistance of the general order of a 'thousand ohms connected in theloop aerial; and an operating circuit coupled to said symmetricalcombination of loop and open aerials.

15. Three-dimensional directive radio receiving apparatus comprising aclosed loop aerial, an open aerial adjacent thereto; means for movingsaid aerials simultaneously to any desired angular position in space;anf adjustable coupling between said aerials for equalizingvYandopposing the static energies received bythe aerials; and a receivingcircuit `coupled to said 'aerial system.

16. Directional'radio receiving apparatus comprising a closed loopaerial, an open aerial; means for moving said aerials simultaneously toposition the'opeii aerial normal to the transmitted wave-front; saidopen aerial having a .lumped capacity intermediate its ends; adjustablecoupling means between said aerials for equalizing and opposing thestatic energies received thereby; andA areceiving circuit coupled withsaid aerial system. l

17. A three-dimensional directive radio lsystem comprising a closed loopaerial, an' open aerial inductively coupled to but otherwise insulatedfrom said loop aerial; means permitting simultaneousy movement of saidpoint, said open 'aerials to any' desired angular position in space; andan operating circuit coupled to said coupled aerials.

18.- A three-dimensional directive radio system comprising acl'osed loopaerial; an

' about a common open' aerial; and means for aerial about its diameter,said diameter being at right angles tothe open aerial itself, saidaerials' being symmetrically` disposed point and means permittingthe'simultaneous movement of -the open aerial to any-desiredangularlrposition in space. 19. A three-dimensional j directive radiosystem com rising a closed loop -aerial and an open aerial)arrangedsymmetrically about a common point; the loop aerial beingswinging the loop .aerial being mounte the horizontal and vertical axesrespectively circuit associated with lsaid A mounted to be rotatableabout its horizontal and vertical axes res ectively; and the open to berotatable4 about of the loop andsimultaneously tation of the loopaerial.

20. A three-dimensional directive radio system comprising a anopenaerial arranged symmetrically about a common point; the loop aerialbeing mounted to be swung about anpaxis substantially `a't'right angles'to the vopen aerial itself; and the open aerial being mounted to be swunbodily and simultaneously with the loop aerial about'avdiametrical axisof the oop. l'

21. A'three-dimensional directive radio with said roclosed loop' aerialVand system comprising a closed loop aerial and an open aerialsymmetrically arranged together about a common for. simultaneouslyswinging both the aerials about the horizontal and vertical axes oftheloop aerial. f

22. A three-dimensional directive radio system comprising a closed loopaerial and an open aerial arranged symmetrically together about a commonpoint; and means for swinging'the loop aerial about its horizontal andvertical axes respectively, and for simultaneously movin the open aerialwhile preserving its relation with the loop'v aerial.

23. AVthree-dimensional directive radio point; and means systemcomprising a closed loop aerial and an open aerial arranged togethersymmetrically about a'cmmon point; and means for swinging both aerialssimultaneously within a ran of 360 to any desired angular position inspace.

24. A three-dimensional directive, radio system comprising-a closed loopaerial; two metal rods mounted substantially diametri-- cally of theloop aerial and symmetrically thereto about a common point, said rodsconstituting parts of an open aerial; means for couplin the closed andopen aerials; and means or swin 'ng both aerials simultaneously to anygl space.

25. Directional radioapparatus comprising' two aerials, one being of theclosed condenser-tuned loop type, and another being of the open antennatype, said two aerials beinglocated at approximately the same point inspace relative to the length of transmitted esired 'angular position inlll ranged h orizontall relative to earth and symmetrically relative tothe loop aerial; the4 open antenna aerial also being insulated from theloop aerial but coupledthereto; and anv operating circuit-coupled withvsaid aerial system. t .l

26. Directional radio apparatus compris ing two aerials, one being ofthe closed'condenser-tuned loop type, and another being of two aerials,

system including the open antenna type; said two aerials being locatedat approxlmatelythe same point in space relativeto the length oftransmitted waves; the open antenna aerial being arranged horizontally7relative to earth and symmetrically relative to the loop aerial; theloop aerial containing a' lumped resistance; the open antenna aerialbeing insulated from the lpop aerial but coupled thereto; and anoperating circuit coupled .with said aerial system.

27. Radio receiving apparatus comprising two aerials, one being of theclosed condenser-tuned loop type, and another being of the open antennatype, said two aerials being located at approximately the same point inspace relative to the length of transmitted waves; means for moving theopen antenna relative tothe earth to causefit to be normal to tiltedtransmission; the open antenna aerial being insulated from the-loopaerial but coupled thereto; and an operating circuit coupled to saidaerial system.

28. Radio receiving apparatus comprising ser-tuned loop type, andanother being an open antenna, said two aerials being located atapproximately the same point in space relative to the length oftransmitted waves; means for tilting the open antenna relative to theearth to cause it to be normal to tilted transmission; the open aerialbeing insulated'from the loop but coupled thereto; means permittingrotation of the loop aerial; and an operating circuit coupled with saidaerial system.

29. Three-dimensional directive radio receiving apparatus whichcomprises an aerial two aerials of different directionalcharacteristics, namely a closed loo aerial and an open antenna aerial,said aerialsbeing vdisposed symmetrically with respect to one anotherand the open aerial being in substantially the same planel with theclosed aerial; the two aerials being inductively connected together; theopen aerial forming no part of the closed aerial; the closed aerialbeing insulated from earth; the open aerial being arranged generallyparone being of the closed condenallel tc the earth; means for tiltingthe open aerial about a horizontal axis to submerge its characteristiccurve and decrease the effects of static; said arrangement securinguni-lateral reception and a null point from overhead; said apparatusincluding also a third circuit, of reception by the above aerial system*and an inductive coupling between said thlrd circuit and said system andtranserring currents in phase between said third circuit and the twoaerials; said last named coupling and the coupling between the twoaerials, being reversible and adjustable and v permitting equalizationand concellation of static energies.

30. Directional radio apparatus comprising two aerialsof differentdirectional characteristics coupled together, and means permittingsimultaneous movement of both said aerials to desired positions of theaerial system as positions `relative to one another.

31. Three-dimensional directive radio receiving apparatus comprising twoaerials of different irectional characteristics coupled together; meanspermitting simultaneous movement of both aerials to any desired angularposition in space while preserving' their positions relative to onevanother; and means for observing reception by said aerial system whenthe latter is in any' such angular position.

32. Directional radio apparatus comprising two aerials of differentdirectional characteristics insulated from one another but coupledtogether; and means permittin simultaneous movement of both coupleaerials to any desired angular position in ,space while preserving theirvpositions relativ'e to one another; the coupling between said aerialsbeing adjustable and reversible.

33. Directional radio apparatus comprising two aerials of differentdirectional characteristics mounted in fixed relation to one another andcoupled together; and means for simultaneously moving said aerials toany desired angular position in space while reservin their fixedrelation to one anot er. GRE NLEAF -WHITTIER PICKARD.

a whole while preserving theirl

